1. Field of the Invention
The present invention relates to materials processing involving a chemical and/or a physical action(s) or reaction(s) of a component or between components. More specifically, the present invention uses irradiation of components in a reactor to continuously process relatively large quantities of materials.
2. General Background and State of the Art
Apparatus for materials processing consisting of coaxial cylinders that are rotated relative to one another about a common axis, the materials to be processed being fed into the annular space between the cylinders, are known. For example, U.S. Pat. No. 5,370,999, issued Dec. 6, 1994 to Colorado State University Research Foundation discloses processes for the high shear processing of a fibrous biomass by injecting a slurry thereof into a turbulent Couette flow created in a xe2x80x9chigh-frequency rotor-stator devicexe2x80x9d, this device having an annular chamber containing a fixed stator equipped with a coaxial toothed ring cooperating with an opposed coaxial toothed ring coupled to the rotor. U.S. Pat. No. 5,430,891, issued Aug. 23, 1994 to Nippon Paint Co., Ltd. discloses processes for continuous emulsion polymerization in which a solution containing the polymerizable material is fed to the annular space between coaxial relatively rotatable cylinders.
U.S. Pat. Nos. 5,279,463, issued Jan 18, 1994, and U.S. Pat. No. 5,538,191, issued Jul. 23, 1996, both having the same applicant as the present invention, disclose methods and apparatus for high-shear material treatment, one type of the apparatus consisting of a rotor rotating within a stator to provide an annular flow passage.
It is known in the art to process substances in the form of liquids, solids, gasses, or various combinations of the three by applying energy in the form of, for example, heat, visible, ultraviolet, or infrared light as well as longitudinal pressure oscillations, microwave, X-ray or gamma irradiations. It is common to use radiation to increase reaction rates or sterilize substances for human consumption, for example.
Microwaves cause heating by two principal methods: dipolar polarization and conduction. As the microwave frequency increases, for example from about 2.5 GHz found in a typical household microwave oven, to perhaps 20 GHz, the microwave effects increase due to higher efficiency of absorption. However, the penetration depth of the radiation decreases as the frequency increases. Water in an open container, which is transparent to microwave radiation, will boil in a standard 2.5 GHz microwave oven in approximately 3 minutes. At 20 GHz, the water would theoretically boil in 2 to 3 seconds. However, at this high frequency, the penetration depth of the microwaves is very small, perhaps to the order of xe2x85x9 of an inch. The interior bulk of the solution is untreated. In household applications, the frequency chosen for microwave ovens is about 2.5 GHz, which provides for a limited efficiency of absorption. A higher frequency would increase absorption, and thereby heating, but the penetration depth would decrease. The outer portions of the materials would become very hot, but the interior volume would be poorly heated. In other words, the lower frequencies promote more even heating throughout the volume, but the temperature rise is at a relatively slow rate.
Microwave radiation can increase reaction rates several hundred fold when applied to certain chemical processes. Typically, the substances are placed into reactor vessels, which are then placed inside microwave ovens operating at preselected wavelengths or frequencies. As the microwave radiation enters the materials inside the reactor, pressure and heat increase and the chemical reaction is enhanced. The processing takes place in relatively small batches, and as such is not feasible for production of industrial quantities of processed materials. There have been no practical microwave-assisted reactor that can produce relatively large quantities of materials in a continuous process.
In processing industrial quantities of chemical reactants, it would be preferable to apply high frequency electromagnetic radiation throughout the entire volume at essentially the same time, rather than just up to the penetration depth of the radiation. This would reduce the possibility of non-homogeneous reactions resulting in the production of undesirable by-products or results caused by uneven heating and mixing.
It is also known to use ultraviolet light to sterilize substances for human consumption. In one system, ultraviolet emitting tubes are placed in a tank of water contaminated with pathogens such as viruses or bacteria. The distances between the tubes is calculated so that any pathogen in the tank will be close enough to the tubes to receive a lethal dose of radiation. However, the tubes quickly become covered in slime or other contaminates, reducing the emitted ultraviolet radiation to a level where some pathogens can survive, leading to possible illness or death when the water is consumed.
It would be desirable to provide a method and apparatus for irradiating relatively large quantities of materials quickly and thoroughly.
Accordingly, an object of the present invention is to provide a method and apparatus for irradiating relatively large quantities of materials quickly and thoroughly. The invention is concerned especially, but not exclusively, with processes and apparatus that modify materials or compounds in solution or suspension.
The material is mixed and a chemical or biological reaction is controlled by the introduction or removal of energy in any form, including energy in the form of heat, visible, ultraviolet, or infrared light as well as longitudinal pressure oscillations, microwave, X-ray and gamma irradiations. The energy can be any frequency of electromagnetic-wave irradiation.
The method for processing materials of the present invention can include: passing materials to be processed in a flow path through an annular processing passage between two closely spaced smooth surfaces provided by respective inner and outer cylindrical apparatus members at least one rotating relative to the another; and irradiating the materials in the processing passage with processing energy through a wall of one of the two members. The energy applied to the processing passage can be, for example, electromagnetic energy of microwave frequency, light, X-rays, gamma radiation and ultrasonic longitudinal vibrations. The cylindrical apparatus members can rotate relative to one another about respective longitudinal axes that are coaxial with one another so that the radial spacing of the two surfaces is constant circumferentially thereof. The apparatus members can be moved so as to produce a linear velocity between their operative surfaces relative to one another of at least 0.5 meter per second. One or both of the surfaces can be coated with catalytic material that enhances at least one of chemical, biochemical and biocidal reactions in the processing passage. The cylindrical apparatus members rotate relative to one another about respective horizontally or vertically oriented parallel longitudinal axes. The outer member remains substantially stationary while the inner member rotates to produce a linear velocity between their operative surfaces relative to one another. The processing energy irradiating the materials in the processing passage can pass through the wall of the outer member and can enter the processing passage through at least one window in the wall of the outer member. The processing energy can be electromagnetic energy produced by at least one microwave tube connected to at least one port in the wall of the outer member leading to the at least one window in the wall of the outer member. The frequency of the electromagnetic energy can encompass the entire spectrum of electromagnetic waves including the spectrum between 2.5 GHz and 50 GHz. The processing energy can also be light irradiation introduced into the annular processing passage through at least one laser light guide. The processing energy can be produced by at least one transducer. The relative rotation produces eddies in the materials to be processed. The height of the annular processing passage can be less than the penetration depth of the electromagnetic energy into the materials to be processed. The invention can include producing eddies in the materials to circulate the molecules of the materials to be processed past at least one window to provide substantially even exposure on a molecular level of the materials to be processed. The material to be processed can be substantially opaque to the processing energy and the eddies can circulate the materials to be processed past the processing energy to provide surface renewal so that the molecules of the materials to be processed are substantially evenly exposed to the processing energy. The materials to be processed can include a combination of a gas and a liquid; a liquid and a solid; or a gas, liquid and solid, for example. The height of the annular processing passage can be small enough and the cylindrical apparatus members can rotate relative to each other rapidly enough so that the gas is emulsified into the liquid to produce a gas/liquid emulsification, thereby increasing the interfacial contact between the gas and liquid. Also, the height of the annular processing passage can be small enough, the cylindrical apparatus members can rotate relative to each other rapidly enough and the two closely spaced smooth surfaces can be smooth enough so that the materials to processed are essentially free of Taylor vortices. The materials to processed can then be irradiated to facilitate a reaction in the essentially Taylor vortices-free material.
The apparatus for processing materials of the present invention can include two cylindrical apparatus members mounted for rotation relative to one another, and defining two closely spaced smooth surfaces providing an annular processing passage constituting a flow path for the material, and an energy source for applying processing energy to the processing passage through a wall of the two members. The energy applied to the processing passage can be, for example, any one of electromagnetic energy of microwave frequency, light, X-rays, gamma radiation and ultrasonic longitudinal vibrations. The cylindrical apparatus members can be mounted to rotate relative to one another about respective longitudinal axes that are coaxial with one another so that the radial spacing of the two surfaces is constant circumferentially thereof. The apparatus members can be moved so as to produce a linear velocity between their operative surfaces relative to one another of at least 0.5 meter per second. One or both of the surfaces can be coated with catalytic material that enhances at least one of chemical, biochemical and biocidal reactions in the processing passage. The cylindrical apparatus members can rotate relative to one another about respective horizontally or vertically oriented parallel longitudinal axes. The outer member can remain substantially stationary while the inner member rotates to produce a linear velocity between their operative surfaces relative to one another. The processing energy can irradiate the materials in the processing passage passes through the wall of the outer member. There can be at least one window in the wall of the outer member through which the processing energy enters the processing passage and irradiates the materials. The processing energy can be electromagnetic energy produced by at least one microwave tube connected to at least one port in the wall of the outer member leading to the at least one window in the wall of the outer member. The frequency of the electromagnetic energy can encompass the entire spectrum of electromagnetic waves including the spectrum between 2.5 GHz and 50 GHz. The processing energy an be light irradiation introduced into the annular processing passage through at least one laser light guide. At least one transducer can produce the processing energy. The relative rotation can produce eddies in the materials to be processed. The height of the annular processing passage can be less than the penetration depth of the electromagnetic energy into the materials to be processed. Eddies can be produced in the materials for circulating the molecules of the materials to be processed past at least one window to provide substantially even exposure on a molecular level of the materials to be processed. The material to be processed can be substantially opaque to the processing energy. Eddies can be produced in the materials for circulating the materials to be processed past the processing energy to provide surface renewal so that the molecules of the materials to be processed are substantially evenly exposed to the processing energy. The materials to be processed can include a gas and a liquid, the height of the annular processing passage can be small enough and the cylindrical apparatus members can rotate relative to each other rapidly enough so that the gas is emulsified into the liquid to produce a gas/liquid emulsification, thereby increasing the interfacial contact between the gas and liquid; and the gas/liquid emulsification can be irradiated with the processing energy through a wall of one of the two members to facilitate a reaction between the gas and liquid. The height of the annular processing passage can be small enough, the cylindrical apparatus members can rotate relative to each other rapidly enough and the two closely spaced smooth surfaces can be smooth enough so that the materials to processed are essentially free of Taylor vortices; and the materials to be processed can be irradiated with the processing energy through a wall of one of the two members to facilitate a reaction in the essentially Taylor vortices-free material.